Secondary battery

Abstract

An embodiment relates to a secondary battery without a cap-up. An embodiment relates to a secondary battery in which deformation of a safety vent can be prevented. An embodiment addresses the technical problem of providing a secondary battery in which a buffer member is disposed in an insertion part of a safety vent, and thus deformation of the safety vent can be prevented. To this end, a secondary battery according to an embodiment comprises: a case; an electrode assembly accommodated in the case; and a cap assembly for sealing the case, wherein the cap assembly includes a cap-down and a safety vent on the cap-down, the safety vent includes a first central region and a first edge region, the first edge region includes an insertion part formed by a plurality of bent parts, a buffer member is disposed in the insertion part, and the tensile strength of the buffer member is greater than the tensile strength of the safety vent.

Description

secondary battery

[0001] The embodiment relates to a secondary battery.

[0002] Secondary batteries, unlike non-rechargeable primary batteries, are rechargeable and dischargeable. Low-capacity secondary batteries are used in small, portable electronic devices such as smartphones, feature phones, laptops, digital cameras, and camcorders, while large-capacity secondary batteries are widely used as power sources for motor drives and power storage in hybrid and electric vehicles. These secondary batteries include an electrode assembly comprising a positive and negative electrode, a case housing the electrode assembly, and electrode terminals connected to the electrode assembly.

[0003] The above-described information disclosed in the background technology of this invention is only intended to improve understanding of the background of the present invention, and therefore may include information that does not constitute prior art.

[0004] The embodiment provides a secondary battery having improved safety.

[0005] The embodiment provides a secondary battery capable of preventing deformation of a safety vent.

[0006] A secondary battery according to an embodiment includes a case; an electrode assembly accommodated inside the case; and a cap assembly sealing the case, wherein the cap assembly includes a cap down and a safety vent on the cap down, the safety vent includes a first central region and a first edge region, the first edge region includes an insertion portion formed by a plurality of bending portions, a buffer member is disposed in the insertion portion, and a tensile strength of the buffer member is greater than a tensile strength of the safety vent.

[0007] The tensile strength of the above buffer member is 4 to 100 times the tensile strength of the above safety vent.

[0008] The tensile strength of the above buffer member is 200 MPa to 700 MPa.

[0009] The above safety vent is the outermost surface of the upper portion of the secondary battery.

[0010] The cap down includes a second central region and a second edge region, and the second central region and the second edge region overlap the first central region in a first direction, which is a height direction of the secondary battery, and the first edge region and the second edge region do not overlap in the first direction, and a first notch is arranged in the first central region and a second notch is arranged in the second central region.

[0011] The first edge region includes a first unbending portion, a second unbending portion, and a bending portion, the bending portion being connected to the first unbending portion and the second unbending portion, and the insertion portion being formed in a region between the first unbending portion and the second unbending portion.

[0012] It further includes an insulating member arranged in the first central region and the second edge region, wherein the buffer member and the insulating member are in contact.

[0013] It further includes an insulating member arranged in the first central region and the second edge region, wherein the buffer member and the insulating member are spaced apart from each other by a first distance.

[0014] The second unbending portion and the second edge region are spaced apart by a second distance, the second distance being 0.2 mm to 0.5 mm, and the first distance and the second distance are different.

[0015] The buffer member has a first thickness, the first unbending portion has a 2-1 thickness, the second unbending portion has a 2-2 thickness, the radius of curvature of the bending portion is 0.3 mm to 0.5 mm, and when the thicknesses of the 2-1 thickness and the 2-2 thickness are 0.3 mm to 0.5 mm, the first thickness is 0.3 mm to 0.5 mm.

[0016] The first edge region has a third thickness, the cap assembly has a fourth thickness, and the fourth thickness satisfies the following mathematical expression.

[0017] [Mathematical formula]

[0018] T3 ≤ T4 ≤ T3 * 1.1

[0019] It further includes an insulating member disposed in the first central region and the second edge region, wherein the insulating member is disposed on the upper surface and the side surface of the second edge region.

[0020] The end of the buffer member does not overlap the end of the second unbending portion in the first direction.

[0021] The buffer member includes a first buffer member and a second buffer member, and the tensile strengths of the first buffer member and the second buffer member are different.

[0022] The thicknesses of the first buffer member and the second buffer member are different.

[0023] A secondary battery according to an embodiment further includes a fixing member disposed in the insertion portion and in contact with the buffer member, wherein the buffer member and the fixing member include different materials.

[0024] The above buffer member comprises a metal, and the above fixing member comprises a resin material.

[0025] A secondary battery according to an embodiment further includes an insulating member disposed in the first central region and the second edge region, wherein the fixing member and the insulating member include the same material.

[0026] The first edge region includes a first unbending portion, a second unbending portion, and a bending portion, the bending portion is connected to the first unbending portion and the second unbending portion, the insertion portion is formed in an area between the first unbending portion and the second unbending portion, and the fixing member is disposed on a side surface of the insertion portion and the second unbending portion.

[0027] At least one of the two ends of the buffer member includes a curved surface.

[0028] It includes a pattern portion formed in at least one of the above bending portion, the first unbending portion, and the second unbending portion.

[0029] The above bending portion includes a pattern, wherein the pattern is a hole or a groove.

[0030] A buffer portion adjacent to the first notch is included, and the thickness of the buffer portion is smaller than the thickness of the safety vent in which the first notch is formed.

[0031] The thickness of the above buffer portion decreases as it gets closer to the first notch.

[0032] A secondary battery according to an embodiment includes a cap assembly that does not include a cap-up. Accordingly, the thickness of the cap assembly can be reduced. Accordingly, the size of the electrode assembly can be increased. Accordingly, the charging characteristics of the secondary battery can be improved.

[0033] A secondary battery according to an embodiment may include a safety vent and a cap down. The edge region of the safety vent includes a bending portion. The safety vent includes an insertion portion formed by the bending portion.

[0034] The buffer member is positioned in the insertion portion. The buffer member includes a material having a tensile strength greater than that of the safety vent. Accordingly, the safety vent can be prevented from being deformed by the buffer member.

[0035] Accordingly, the position or shape of the notch can be prevented from changing due to deformation of the safety vent. Accordingly, the secondary battery according to the embodiment can have improved reliability and lifespan.

[0036] The safety vent and the cap down can be spaced apart by a set distance. Specifically, the unbending portion and the edge area of ​​the cap down can be spaced apart by a set distance. Accordingly, electrical connection between the safety vent and the cap down can be prevented. Accordingly, when an event occurs in the secondary battery, the connection between the unbending portion and the cap down can be prevented from spreading a fire.

[0037] The edge area of ​​the above safety vent may have a set thickness. Accordingly, the thickness of the cap assembly can be prevented from increasing. Accordingly, the charging capacity of the secondary battery can be improved.

[0038] However, the effects that can be obtained through the present invention are not limited to the effects described above, and other technical effects that are not mentioned can be clearly understood by those skilled in the art from the description of the invention described below.

[0039] The following drawings attached to this specification illustrate preferred embodiments of the present invention, and together with the detailed description of the invention described below, serve to further understand the technical idea of ​​the present invention, and therefore, the present invention should not be interpreted as being limited to matters described in such drawings.

[0040] Figure 1 is a perspective view of a secondary battery according to an embodiment.

[0041] Figure 2 is a cross-sectional view taken along the AA' area of ​​Figure 1.

[0042] Figure 3 is an enlarged view of area A of Figure 1.

[0043] Figures 4 to 16 are other enlarged views of area A of Figure 1.

[0044] Figure 17 is an enlarged view of area B of Figure 3.

[0045] Fig. 18 is a perspective view of a secondary battery according to another embodiment.

[0046] FIGS. 19 and 20 are perspective views of a battery pack including a battery module according to an embodiment.

[0047] FIGS. 21 and 22 are perspective and side views of a vehicle including a battery pack according to an embodiment.

[0048] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Prior to this, terms or words used in this specification and claims should not be interpreted as limited to their typical or dictionary meanings, and should be interpreted with meanings and concepts that conform to the technical spirit of the present invention based on the principle that the inventor can appropriately define the concept of a term to best explain his or her own invention. Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are only some of the most preferred embodiments of the present invention and do not represent all of the technical spirit of the present invention. Therefore, it should be understood that various equivalents and modified examples may exist as substitutes for them at the time of filing this application.

[0049] Additionally, when used herein, the terms "comprise", "include" and / or "comprising", "including" specify the presence of stated features, numbers, steps, operations, elements, elements and / or groups thereof, but do not preclude the presence or addition of one or more other features, numbers, operations, elements, elements and / or groups thereof.

[0050] Additionally, to facilitate understanding of the invention, the attached drawings may not be drawn to scale and some components may be exaggerated in size. Furthermore, identical components may be assigned the same reference numbers in different embodiments.

[0051] The statement that two compared objects are "identical" means "substantially identical." Therefore, "substantially identical" may include deviations considered low in the art, such as deviations of less than 5%. Furthermore, uniformity of a parameter over a given region may imply uniformity on average.

[0052] Although the terms first, second, etc. are used to describe various components, these components are not limited by these terms. These terms are used only to distinguish one component from another, and unless otherwise specified, a first component may also be a second component.

[0053] Throughout the specification, unless otherwise specifically stated, each element may be singular or plural.

[0054] Any configuration being placed “on top (or bottom)” of a component or “on top (or bottom)” of a component may mean not only that any configuration is placed in contact with the top (or bottom) of the component, but also that other configurations may be interposed between the component and any configuration placed on (or under) the component.

[0055] Additionally, when it is described that a component is “connected,” “coupled,” or “connected” to another component, it should be understood that the components may be directly connected or connected to each other, but that other components may also be “interposed” between the components, or that each component may be “connected,” “coupled,” or “connected” through another component. Furthermore, when it is said that a part is electrically coupled to another part, this includes not only cases where they are directly connected, but also cases where they are connected with another element in between.

[0056] When reference is made throughout the specification to “A and / or B,” this means A, B, or A and B, unless otherwise stated. In other words, “and / or” includes all or any combination of the listed items. When reference is made to “C through D,” this means C or more and D or less, unless otherwise stated.

[0057] The terminology used herein is for the purpose of describing embodiments of the present disclosure and is not intended to be limiting of the present disclosure.

[0058] In exemplary embodiments of a cylindrical battery according to the embodiment of the present disclosure, one of the cylindrical batteries is selected and the selected battery is described as having a general structure, and in the case of a generally applicable technology, the general structure of the cylindrical battery is described.

[0059] Hereinafter, a secondary battery according to an embodiment will be described with reference to the drawings.

[0060] In the following description, the first direction (1D) is defined as the thickness (height) direction of the secondary battery. The second direction (2D) is defined as the diameter (width) direction of the secondary battery.

[0061] As illustrated in FIGS. 1 to 3, the secondary battery (1000) includes a case (100), an electrode assembly (200), a cap assembly, and an insulator. The cap assembly may include a safety vent (500) and a cap down (600). In detail, the cap assembly does not include a cap up.

[0062] The electrode assembly (200) may be accommodated in the case (100). For example, the electrode assembly (200) may be accommodated in the case (100) together with an electrolyte.

[0063] The electrode assembly (200) may include a first electrode (210), a second electrode (220), and a separator (230). The separator (230) may be disposed between the first electrode (210) and the second electrode (220). The first electrode (210), the second electrode (220), and the separator (230) may be wound in a jelly-roll shape.

[0064] The first electrode (210) includes a first substrate and a first active material layer. The first active material layer may be disposed on at least one of one side and the other side of the first substrate. The first electrode (210) includes a first non-coated portion. The first non-coated portion is an area where the first active material layer is not disposed.

[0065] The first non-coated portion may be coupled with the first electrode tab (410). For example, the first non-coated portion and the first electrode tab (410) may be coupled by welding. The first electrode tab (410) may extend to the outside of the electrode assembly. Accordingly, the first electrode tab (410) may be coupled with the cap assembly. Specifically, the first electrode tab (410) may be coupled with the cap down (600). Accordingly, the first electrode (210) may be electrically connected to the cap assembly through the first electrode tab (410).

[0066] The second electrode (220) includes a second substrate and a second active material layer. The second active material layer may be disposed on at least one of one side and the other side of the second substrate. The second electrode (220) includes a second non-coated portion. The second non-coated portion is an area where the second active material layer is not disposed.

[0067] The second non-conductive portion may be coupled with the second electrode tab (420). For example, the second non-conductive portion and the second electrode tab (420) may be coupled by welding. The second electrode tab (420) may extend to the bottom portion (110) of the case. Accordingly, the second electrode tab (420) may be coupled with the case (100). Accordingly, the second electrode (220) may be electrically connected to the case (100) through the second electrode tab (420).

[0068] The first electrode (210) may be an anode. For example, the first substrate may include aluminum. In addition, the first active material layer may include a transition metal oxide. The second electrode (220) may be an anode. For example, the second substrate may include copper or nickel. In addition, the second active material layer may include graphite.

[0069] The separator (230) can prevent short circuiting between the first electrode (210) and the second electrode (220) while allowing movement of lithium ions. For example, the separator (230) can include a polyethylene film, a polypropylene film, or a polyethylene-polypropylene film.

[0070] The electrode assembly (200) may be coupled with the center pin (250). The center pin (250) may have a hollow, circular pipe shape. The center pin (250) may be coupled to the core portion of the electrode assembly (200). The center pin (250) may include steel, a steel alloy, nickel-plated steel, a nickel-plated steel alloy, aluminum, an aluminum alloy, or polybutylene terepthalate. The center pin (250) may suppress deformation of the electrode assembly (200) during charging and discharging of the secondary battery. In addition, the center pin (250) may serve as a passage for gas generated internally. The center pin may be omitted.

[0071] The case (100) forms the outer shape of the secondary battery together with the cap assembly. The case (100) may include a cylindrical body portion (120) and a bottom portion (110) connected to one side of the body portion. A beading portion (130) deformed toward the inside may be positioned on the body portion, and a crimping portion (140) bent toward the inside may be positioned on the opening side end of the body portion.

[0072] The beading portion (130) can prevent the electrode assembly from moving inside the case (100). In addition, the beading portion (130) can support the gasket (900) and the safety vent (500). The crimping portion (140) can firmly fix the safety vent (500) by pressing the edge of the safety vent (500) through the gasket (500). For example, the case (100) can include steel, a steel alloy, nickel-plated steel, a nickel-plated steel alloy, aluminum, an aluminum alloy, or polybutylene terephthalate.

[0073] The cap assembly can be coupled to the upper portion of the case. The cap assembly can seal the opening of the body portion (120). Accordingly, the electrode assembly (200) can be sealed by the cap assembly.

[0074] The above safety vent (500) can be fixed to the inside of the crimping portion through a gasket (900) to seal the case.

[0075] A safety vent (500) may be located at the uppermost side of the cap assembly. The safety vent (500) may be connected to the cap down (600). For example, the safety vent (500) may include a protrusion that convexly protrudes downward. The protrusion may be connected to the cap down (600). In addition, the safety vent (500) may include at least one notch located around the protrusion. However, the embodiment is not limited thereto. The safety vent (500) may be connected to the cap down (600) without a separate protrusion.

[0076] When gas is generated due to overcharging or abnormal operation of the secondary battery, the safety vent (500) may be deformed upward by pressure, separated from the cap down (600), and cut along the notch. The cut safety vent may release the gas to the outside, thereby preventing an explosion of the secondary battery.

[0077] The above cap assembly does not include a cap-up. The safety vent (500) can simultaneously function as a current interrupting device (CID) and a cap-up. The uppermost surface of the upper portion of the secondary battery can be the safety vent (500).

[0078] The cap down (600) may be positioned below the safety vent (500). The cap down may include at least one of a first opening (OP1) and a second opening (OP2). The first opening (OP1) may partially expose the safety vent. In addition, the second opening (OP2) may discharge the gas. An insulating member (700) may be positioned between the safety vent and the cap down to insulate the safety vent and the cap down.

[0079] The above insulator may include a first insulator (310) and a second insulator (320).

[0080] The first insulator (310) may be disposed between the electrode assembly (200) and the cap assembly. The first insulator (310) may include a third opening (OP3) and a fourth opening (OP4). The first electrode tab (410) may be coupled to the cap down (600) by the third opening (OP3). When gas is generated by an event of the electrode assembly, the gas may be discharged by at least one of the third opening (OP3) and the fourth opening (OP4). The second electrode and the cap assembly may be insulated by the first insulator (310).

[0081] A second insulating plate (320) may be disposed between the bottom portion (120) and the electrode assembly. The second insulating plate (320) may include at least one of a fifth opening (OP5) and a sixth opening (OP6). Either of the fifth opening (OP5) and the sixth opening (OP6) may be omitted depending on the design of the electrode assembly. In addition, the number and position of either of the fifth opening (OP5) and the sixth opening (OP6) may vary depending on the design of the electrode assembly.

[0082] For example, when the electrode assembly includes a fifth opening, the second electrode tab (420) can be coupled to the bottom portion (110) by the fifth opening (OP5). When gas is generated by an event of the electrode assembly, the gas can move upward and be discharged by the center pin (250) and the sixth opening (OP6). The first electrode and the case can be insulated by the second insulator (320).

[0083] Figure 3 is an enlarged view of area A of Figure 2. Figure 3 is an enlarged view of the cap assembly.

[0084] Referring to FIG. 3, the safety vent (500) may be positioned above the cap down (600). The cap down (600) may be positioned between the safety vent (500) and the electrode assembly (200). The safety vent (500) and the cap down (600) may have a circular shape. The outer diameter of the safety vent (500) may be larger than the outer diameter of the cap down (600).

[0085] The safety vent (500) and the cap down (600) may comprise metal. For example, the safety vent (500) may comprise aluminum or an aluminum alloy. The cap down (600) may comprise at least one of aluminum or an aluminum alloy, steel, a steel alloy, nickel, and a nickel alloy.

[0086] The above safety vent (500) can be divided into a first central area (CA1) and a first edge area (OA1) depending on the location.

[0087] The above safety vent (500) may include a first notch (N1). The first notch (N1) may be formed in the first central area (CA1).

[0088] The first central region (CA1) may include a downwardly convex region. Accordingly, the first central region (CA1) may include a protrusion (PA). The protrusion (PA) may extend in the direction of the electrode assembly. As described above, the protrusion may be omitted. Hereinafter, a description will be given focusing on a case where the safety vent (500) includes a protrusion.

[0089] The above protrusion (PA) can be combined with the cap down (600). For example, the protrusion (PA) and the cap down (600) can be combined by welding. The first notch (N1) can be formed in an area other than the protrusion (PA).

[0090] The cap down (600) may be coupled with the first electrode tab (410). For example, the cap down (600) and the first electrode tab (410) may be coupled by welding. Accordingly, the first electrode (210) may be electrically connected to the safety vent (500) by the first electrode tab (410) and the cap down (600). Accordingly, when the first electrode (210) is a positive electrode, the safety vent (500) may become a positive terminal.

[0091] The cap down (600) may be divided into a second central region (CA2) and a second edge region (OA2) depending on the location. The second central region (CA2) and the second edge region (OA2) may overlap with the first central region (CA1) in the first direction (1D). In addition, the second edge region (OA2) may not overlap with the first edge region (OA1) in the first direction (1D).

[0092] The cap down (600) may include a first opening (OP1) and a second opening (OP2). As described above, gas generated by an event of the secondary battery may be discharged through the first opening (OP1) and the second opening (OP2).

[0093] The first opening (OP1) may be formed in the second central area (CA2). Accordingly, the second central area (CA2) may be arranged to surround the first opening (OP1).

[0094] The above first opening (OP1) can be covered by the safety vent (500). In detail, the above first opening (OP1) can be covered by the protrusion (PA).

[0095] The second opening (OP2) may be formed between the second central area (CA2) and the second edge area (OP2). The second opening (OP2) may overlap the first central area (CA1) in the first direction (1D). In detail, the second opening (OP2) may overlap an area other than the protrusion (PA) in the first direction (1D).

[0096] The cap down (600) may include a second notch (N2). The second notch (N2) may be formed in the second central area (CA2). The second central area (CA2) may include a 2-1 central area (CA2-1) adjacent to the first opening (OP1) and a 2-2 central area (CA2-2) distant from the first opening (OP1). The thicknesses of the 2-1 central area (CA2-1) and the 2-2 central area (CA2-2) may be different. For example, the thickness of the 2-1 central area (CA2-1) may be smaller than the thickness of the 2-2 central area (CA2-2). The second notch (N2) may be formed in the 2-1 central area (CA2-1).

[0097] The insulating member (700) may be disposed between the safety vent (500) and the cap down (600). The insulating member (800) may be formed in a circular ring shape. The insulating member (800) may be disposed between the first central area (CA1) and the second edge area (OP2). A portion of the cap down (600) may be electrically connected to the safety vent (500) by the protrusion (PA). In addition, another portion of the cap down (600) may be spaced apart from the safety vent (500) by the insulating member (800). Therefore, the safety vent (500) and the cap down (600) may include both a connected area and a non-connected area.

[0098] When an event occurs in the secondary battery, the first notch (N1) may be ruptured by an increase in internal pressure and gas discharge. As a result, the safety vent (500) and the cap down may be separated.

[0099] If the internal pressure exceeds the set pressure, the second notch (N2) may rupture. Consequently, the gas is discharged outside the secondary battery. This prevents the spread of fire within the secondary battery. Consequently, explosion of the battery module or battery pack can be prevented.

[0100] The first notch (N1) may overlap the second opening (OP2) in the first direction (1D). Accordingly, the gas may easily pass through the second opening (OP2) and move to the rupture area of ​​the safety vent formed by the first notch (N1). Accordingly, the gas may easily be discharged to the outside of the secondary battery.

[0101] The above safety vent (500) may include a bending area.

[0102] The first edge area (OA1) may be bent. Specifically, the first edge area (OA1) may be bent in multiple directions. For example, the first edge area (OA1) may include a first bend portion (BP1) and a second bend portion (BP2). For example, the first edge area (OA1) may be bent by curling.

[0103] The above first edge area (OA1) may include a first unbending portion (UBA1), a second unbending portion (UBA2), and a bending portion (BA).

[0104] The first unbending portion (UBA1) may be connected to the first central area (CA1). The bending portion (BA) may be connected to the first unbending portion (UBA1) and the second unbending portion (UBA2). The bending portion (BA) may be positioned between the first unbending portion (UBA1) and the second unbending portion (UBA2).

[0105] The first edge area (OA1) can be bent in the direction of the electrode assembly by the first bending portion (BP1), and can be bent in the direction of the end of the second edge area (OA2) by the second bending portion (BP2).

[0106] The first edge area (OA1) is formed with an insertion portion (IP) by bending. That is, the first edge area (OA1) can be bent while the first unbending portion (UBA1) and the second unbending portion (UBA2) are spaced apart from each other in the first direction (1D). Accordingly, the first edge area (OA1) can include an insertion portion between the first unbending portion (UBA1) and the second unbending portion (UBA2). The insertion portion (IP) can be formed in a circular shape.

[0107] The safety vent (500) may be fixed to the case (100). Specifically, the first edge area (OA1) may be supported by the beading portion (130). A gasket (900) is disposed between the case (100) and the safety vent (500). The case (100) and the safety vent (500) may be insulated by the gasket (900). In addition, the gasket (900) may completely or partially surround the first edge area (OA1). Accordingly, the safety vent (500) may be stably fixed by the gasket (900).

[0108] The first edge area (OA1) may include a plurality of bends. Accordingly, the contact area between the first edge area (OA1) and the gasket (900) may increase. Accordingly, the fixing force of the safety vent (500) may increase. In addition, the corners of the first edge area (OA1) may be formed as curved surfaces. Accordingly, the gasket (900) may be prevented from being damaged by the corners of the first edge area (OA1).

[0109] The first edge area (OA1) may include a bending portion (BA). Accordingly, stress may be generated in the first edge area (OA1) due to the bending portion (BA). For example, compressive stress may be generated in the first edge area (OA1). The shape of the first edge area (OA1) may change due to the stress. Depending on the change in the shape of the first edge area (OA1), the shape of the first central area (CA1) may also change.

[0110] Alternatively, the stress may be transmitted to the first central region (CA1). As described above, the safety vent (500) may include an aluminum-based metal. Accordingly, the aluminum has a low tensile strength. Accordingly, the first edge region (OA1) can be bent by a small force, and the safety vent (500) can be easily deformed by the stress. Accordingly, the shape of the first central region (CA1) may change.

[0111] Accordingly, the shape or position of the first notch (N1) formed in the first central area (CA1) may change. Accordingly, the first notch (N1) may be broken at a pressure other than the set pressure. Accordingly, the lifespan of the secondary battery may be reduced. In addition, the position of the first notch (N1) may be deformed, thereby changing the breakage position of the safety vent. Accordingly, the gas may not be easily discharged.

[0112] To prevent the above-described problem, the secondary battery according to the embodiment may include a buffer member (800).

[0113] The buffer member (800) may be positioned in the first edge area (OA1). The buffer member (800) may be positioned between the first unbending portion (UBA1) and the second unbending portion (UBA2). The buffer member (800) may be positioned in the insertion portion (IP). Accordingly, the buffer member (800) may be fixed to the insertion portion (IP) without a separate welding process.

[0114] The buffer member (800) may include a material having a tensile strength within a set range. For example, the buffer member (800) may include a material having a tensile strength greater than that of the safety vent (500). In addition, the buffer member (800) may include metal.

[0115] For example, the buffer member (800) may include a material having a tensile strength of 4 to 100 times, 10 to 100 times, or 20 to 100 times the tensile strength of the safety vent (500).

[0116] For example, the buffer member (800) may include a material having a tensile strength of 200 MPa or more. In detail, the buffer member (800) may include a material having a tensile strength of 200 MPa to 700 MPa, 300 MPa to 650 MPa, or 400 MPa to 600 MPa. For example, the buffer member (800) may include stainless steel (SUS), cold-rolled steel sheet (SPCE), or nickel-plated cold-rolled steel sheet. However, the embodiment is not limited thereto, and the buffer member (800) may include various metals having a tensile strength in the above range.

[0117] The safety vent (500) may be protected by the buffer member (800). Specifically, the buffer member (800) includes a material having high tensile strength. Therefore, the buffer member (800) is hardly deformed by the stress. Accordingly, the buffer member (800) can prevent deformation of the first edge area (OA1). Accordingly, the shape of the first central area (CA1) can be prevented from changing. Accordingly, the shape or position of the first notch (N1) can be prevented from changing.

[0118] If the buffer member (800) has a tensile strength of less than 200 MPa, deformation may occur in the safety vent (500). Specifically, the safety vent (500) may be deformed as the buffer member (800) is damaged by stress generated in the first edge area (OA1). Accordingly, the shape or position of the first notch may change.

[0119] If the buffer member (800) has a tensile strength exceeding 700 MPa, the selection of materials for the buffer member may be restricted. Accordingly, process costs may increase and process efficiency may decrease.

[0120] Meanwhile, the tensile strength of the buffer member (800) and the safety vent (500) can be measured in various ways. For example, the tensile strength of the buffer member (800) and the safety vent (500) can be measured using various tensile measuring devices. For example, the tensile strength of the buffer member (800) and the safety vent (500) can be measured using a universal material testing machine (Screw Type Universal Testing Machine).

[0121] For example, the tensile strength of the buffer member (800) and the safety vent (500) can be measured by the following method.

[0122] First, a first specimen is taken from the buffer member (800), and a second specimen is taken from the safety vent (500). The first specimen and the second specimen may have a set size (x*y*z). The sizes of the first specimen and the second specimen may be the same or similar. Next, the first specimen is installed in the universal material testing machine. Next, a load is applied to the first specimen until the first specimen is broken. When the first specimen is broken, the tensile measurement of the first specimen is terminated. Next, the tensile strength of the second specimen is measured in the same manner.

[0123] The buffer member (800) and the insulating member (700) may be spaced apart from each other or in contact with each other. For example, the buffer member (800) and the insulating member (700) may be spaced apart from each other by a first distance (D1). Alternatively, the buffer member (800) and the insulating member (700) may be in contact with each other. Even if the buffer member (800) and the insulating member (700) are in contact with each other, when the first notch (N1) and the second notch (N2) are broken, the cap down (600) and the safety vent (500) are not electrically connected.

[0124] The first edge area (OA1) and the second edge area (OA2) may be spaced apart from each other. In detail, the second unbending portion (UBA2) and the second edge area (OA2) may be spaced apart from each other. The second unbending portion (UBA2) and the second edge area (OA2) may be spaced apart from each other by a second distance (D2).

[0125] The drawing illustrates that the first distance (D1) is smaller than the second distance (D2), but the embodiment is not limited thereto. The first distance (D1) may be larger than the second distance (D2). The difference in size between the first distance (D1) and the second distance (D2) may vary depending on the process of forming the safety vent (500), the cap down (600), the insulating member (700), and the buffer member (800).

[0126] The second distance (D2) may have a set range. Specifically, the second distance (D2) may be 0.2 mm or more. For example, the second distance (D2) may be 0.2 mm to 0.5 mm, 0.25 mm to 0.45 mm, or 0.3 mm to 0.4 mm.

[0127] The first edge area (OA1) and the second edge area (OA2) may include a conductive material. Accordingly, when the buffer member (800) and the insulating member (700) come into contact, and the first notch (N1) and the second notch (N2) are broken, the cap down (600) and the safety vent (500) may be electrically connected. Accordingly, the secondary battery may continue to operate, and a fire in the secondary battery may spread. As a result, the secondary battery may explode.

[0128] If the second distance (D2) is less than 0.2 mm, the first edge area (OA1) and the second edge area (OA2) may come into contact due to an error during the process. In addition, if the second distance (D2) is small, the first edge area (OA1) and the second edge area (OA2) may be short-circuited in the air at a voltage within a set range (e.g., 4 V to 5 V).

[0129] If the second distance (D2) exceeds 0.5 mm, the length of the second unbending portion (UBA2) may be shortened. Accordingly, the area on which the buffer member (800) is supported may be reduced. Accordingly, the deformation prevention effect of the buffer member (800) may be reduced. Alternatively, in order to maintain the length of the second unbending portion (UBA2), the size of other components may be reduced. Accordingly, the operating characteristics or lifespan of the secondary battery may be affected.

[0130] The above buffer member (800) may have a set thickness. The thickness of the buffer member (800) may vary depending on the thickness of the unbending portion.

[0131] The above buffer member (800) may have a first thickness (T1). The first unbending portion (UBA1) may have a second-first thickness (T2-1). The second unbending portion (UBA2) may have a second-second thickness (T2-2).

[0132] The first thickness (T1) may vary depending on the curvature of the bending portion (BA). In addition, the curvature of the bending portion (BA) may vary depending on the second-first thickness (T2-1) and the second-second thickness (T2-2). The second-first thickness (T2-1) and the second-second thickness (T2-2) may be the same or similar. Alternatively, the second-first thickness (T2-1) and the second-second thickness (T2-2) may be different.

[0133] For example, when the radius of curvature of the bending portion (BA) is 0.3 mm to 0.5 mm, and the thicknesses of the 2-1 thickness (T2-1) and the 2-2 thickness (T2-2) are 0.3 mm to 0.5 mm, the first thickness (T1) may be 0.3 mm to 0.5 mm. Accordingly, when the safety vent is bent at a curvature within a set range, the deformation of the safety vent can be effectively reduced by the buffer member.

[0134] The first edge area (OA1) may have a third thickness (T3). The cap assembly may have a fourth thickness (T4). The fourth thickness (T4) is the distance from the lowest surface of the cap down (600) to the uppermost surface of the safety vent (500).

[0135] The fourth thickness (T4) may be greater than or equal to the third thickness (T3). In detail, the fourth thickness (T4) may satisfy the following mathematical equation.

[0136] [Mathematical formula]

[0137] T3 ≤ T4 ≤ T3 * 1.1

[0138] If the fourth thickness (T4) deviates from the above mathematical formula, the charging characteristics of the secondary battery may decrease.

[0139] Specifically, if the fourth thickness (T4) exceeds 1.1 times the third thickness (T3), the curvature of the bending portion may be formed to be small. Accordingly, the stress of the safety vent may be reduced. However, since the thickness of the cap assembly increases, the size of the electrode assembly may be reduced. Accordingly, the charging capacity of the secondary battery may be reduced.

[0140] The secondary battery according to the embodiment does not include a cap assembly. Accordingly, the thickness of the cap assembly can be reduced. Accordingly, the size of the electrode assembly can be increased. Accordingly, the charging characteristics of the secondary battery can be improved.

[0141] A secondary battery according to an embodiment may include a safety vent and a cap down. The edge region of the safety vent includes a bending portion. The safety vent includes an insertion portion formed by the bending portion.

[0142] The buffer member is positioned in the insertion portion. The buffer member includes a material having a tensile strength greater than that of the safety vent. Accordingly, the safety vent can be prevented from being deformed by the buffer member.

[0143] Accordingly, the position or shape of the notch can be prevented from changing due to deformation of the safety vent. Accordingly, the secondary battery according to the embodiment can have improved reliability and lifespan.

[0144] The safety vent and the cap down may be spaced apart by a set distance. Specifically, the unbending portion and the edge area of ​​the cap down may be spaced apart by a set distance. Accordingly, electrical connection between the safety vent and the cap down can be prevented. Accordingly, when an event occurs in the secondary battery, the fire spread due to the connection between the unbending portion and the cap down can be prevented. Accordingly, an explosion of the battery module or battery pack can be prevented.

[0145] The edge area of ​​the above safety vent may have a set thickness. Accordingly, the thickness of the cap assembly can be prevented from increasing. Accordingly, the charging capacity of the secondary battery can be improved.

[0146] Hereinafter, secondary batteries according to other embodiments will be described with reference to FIGS. 4 to 16. FIGS. 4 to 16 are other enlarged views of area A of FIG. 2.

[0147] Descriptions of the same content as in the previously described embodiment are omitted. In addition, the same drawing reference numerals are used for the same configuration as in the previously described embodiment.

[0148] Referring to FIG. 4, the insulating member (700) may also be placed on the side surface (LS1) of the second edge region. In detail, the insulating member (700) may be placed on the entire surface or a portion of the side surface (LS1).

[0149] The above insulating member (700) is formed by applying and then curing an insulating resin. The insulating resin has fluidity before curing. Accordingly, the insulating resin can flow toward the side surface (LS1). Subsequently, when the insulating resin is cured, the insulating member (700) can be placed on both the upper surface and the side surface of the second edge region.

[0150] The thickness of the insulating member on the side surface may be smaller than the thickness of the insulating member on the upper surface.

[0151] Since the insulating member is also arranged on the side surface, a short circuit between the cap down and the safety vent can be prevented. In detail, the first edge region and the second edge region can be insulated by the insulating member on the side surface.

[0152] Accordingly, when an event of the secondary battery occurs, the fire of the secondary battery can be prevented from spreading due to a short circuit between the first edge region and the second edge region. Accordingly, an explosion of the secondary battery can be prevented.

[0153] Referring to FIG. 5, the end (E1) of the buffer member (800) may be arranged on the inner side of the end (E2) of the second unbending portion (UBA2). That is, the end (E1) of the buffer member (800) may not overlap with the end (E2) of the second unbending portion (UBA2) in the first direction (1D). Alternatively, referring to FIG. 6, the end (E1) of the buffer member (800) may overlap with the end (E2) of the second unbending portion (UBA2) in the first direction (1D).

[0154] Accordingly, the buffer member (800) can be stably placed in the insertion portion. That is, the front surface of the buffer member (800) can be surrounded by the first edge area (OA1).

[0155] Accordingly, the buffer member (800) can be prevented from being detached from the insertion portion.

[0156] In addition, the first distance (D1) between the buffer member (800) and the insulating member (700) can be increased. Therefore, when the insulating member (800) is placed, it is possible to prevent an insulating material from sticking to the end of the buffer member (800). In addition, the insulating member (800) can be easily placed on the side of the second edge region. In addition, it is possible to prevent the insulating member (800) from being damaged by the buffer member (800) and the insulating member (800) coming into contact.

[0157] Referring to FIGS. 7 and 8, the buffer member may include a plurality of members.

[0158] Referring to FIG. 7, the buffer member (800) may include a first buffer member (810) and a second buffer member (820).

[0159] The first buffer member (810) and the second buffer member (820) may be disposed in the insertion portion. The first buffer member (810) may be disposed on the second unbending portion (UBA2), and the second buffer member (820) may be disposed on the first buffer member (810). The first buffer member (810) and the second buffer member (820) may be in contact. The buffer member (800) may include a plurality of buffer members disposed in the first direction.

[0160] The first buffer member (810) and the second buffer member (820) may include the same material. For example, the first buffer member (810) and the second buffer member (820) may include a material having a tensile strength of 4 to 100 times, 10 to 100 times, or 20 to 100 times the tensile strength of the safety vent (500).

[0161] For example, the first buffer member (810) and the second buffer member (820) may include a material having a tensile strength of 200 MPa or more. In detail, the first buffer member (810) and the second buffer member (820) may include a material having a tensile strength of 200 MPa to 700 MPa, 300 MPa to 650 MPa, or 400 MPa to 600 MPa. For example, the first buffer member (810) and the second buffer member (820) may include stainless steel (SUS), cold-rolled steel sheet (SPCE), or nickel-plated cold-rolled steel sheet.

[0162] Accordingly, the tensile strength of the first buffer member (810) and the second buffer member (820) may be the same or similar.

[0163] Alternatively, the first buffer member (810) and the second buffer member (820) may include a material having a tensile strength of 200 MPa or more. In detail, the first buffer member (810) and the second buffer member (820) may include a material having a tensile strength of 200 MPa to 700 MPa, 300 MPa to 650 MPa, or 400 MPa to 600 MPa. For example, the first buffer member (810) and the second buffer member (820) may include stainless steel (SUS), cold-rolled steel sheet (SPCE), or nickel-plated cold-rolled steel sheet.

[0164] Accordingly, the tensile strength of the first buffer member (810) and the second buffer member (820) may be the same or similar.

[0165] The above buffer member may include a plurality of buffer members. Accordingly, even if one buffer member is damaged, deformation of the safety vent can be prevented by the other buffer members.

[0166] The first buffer member (810) and the second buffer member (820) may have different thicknesses. For example, the thickness of the first buffer member (810) may be greater than the thickness of the second buffer member (820).

[0167] Alternatively, the first buffer member (810) and the second buffer member (820) may include different materials. For example, the first buffer member (810) and the second buffer member (820) may include a material having a tensile strength within the above range.

[0168] Accordingly, the tensile strengths of the first buffer member (810) and the second buffer member (820) may be different. For example, the tensile strength of the first buffer member (810) may be greater than the tensile strength of the second buffer member (820). Pressure may be generated from the cap down (600) toward the safety vent (500) due to the internal pressure of the case. Therefore, the thickness of the first buffer member (810) may be large. Alternatively, the first buffer member (810) may include a material having a high tensile strength. Accordingly, the first buffer member (810) may be prevented from being damaged by the internal pressure. In addition, the second buffer member (820) may include a material having a relatively low tensile strength. Accordingly, the degree of freedom in selecting the material of the buffer member may increase.

[0169] In Fig. 7, the end of the first buffer member (810) and the end of the second buffer member (820) are illustrated as overlapping in the first direction. However, the embodiment is not limited thereto. The end of the first buffer member (810) and the end of the second buffer member (820) may not overlap in the first direction. In addition, the end of the first buffer member (810) and the end of the second buffer member (820) may be arranged on the inner side of the end of the second unbending portion. Alternatively, the end of the first buffer member (810) and the end of the second buffer member (820) may overlap with the end of the second unbending portion in the first direction.

[0170] Referring to FIG. 8, the buffer member (800) may include a first buffer member (810) and a second buffer member (820).

[0171] The first buffer member (810) and the second buffer member (820) may be disposed in the insertion portion. The first buffer member (810) and the second buffer member (820) may be disposed on the second unbending portion (UBA2). The first buffer member (810) and the second buffer member (820) may be in contact. The buffer member (800) may include a plurality of buffer members disposed in the second direction.

[0172] The first buffer member (810) and the second buffer member (820) may include a material having a tensile strength within the range described above. The first buffer member (810) and the second buffer member (820) may include the same material. Alternatively, the first buffer member (810) and the second buffer member (820) may include different materials.

[0173] Accordingly, it can have the same or similar effect as in Fig. 7.

[0174] Referring to FIGS. 9 and 10, a fixing member (830) may be placed in the insertion portion.

[0175] The buffer member (800) and the fixing member (830) may be in contact. The fixing member (830) may be positioned closer to the insulating member (700) than the buffer member (800). The contact area between the buffer member (800) and the insertion portion may be larger than the contact area between the fixing member (830) and the insertion portion.

[0176] The buffer member (800) and the fixing member (830) may include a material having a tensile strength within the range described above. The buffer member (800) and the fixing member (830) may include the same material.

[0177] The above buffer member (800) can be fixed by the fixing member (830). Accordingly, the buffer member (800) can be prevented from being detached from the insertion portion due to external impact.

[0178] The buffer member (800) and the fixing member (830) may include different materials. The buffer member (800) may include a material having a tensile strength within the range described above. The tensile strength of the fixing member (830) may be different from the tensile strength of the buffer member (800). For example, the tensile strength of the fixing member (830) may be lower than the tensile strength of the buffer member (800). Since the fixing member (830) serves to fix the buffer member (800), the material forming the fixing member (830) is not limited by the tensile strength.

[0179] The above-described fixing member (830) may include a metal or a non-metal. For example, the fixing member (830) may include a resin material. For example, the fixing member (830) and the insulating member (700) may include the same material. Accordingly, the fixing member (830) and the insulating member (700) may be formed by the same process. Therefore, process efficiency may be improved.

[0180] Referring to Fig. 10, the fixing member (830) may also be placed on the side surface (LS2) of the second unbending portion. That is, the fixing member (830) may be placed on the insertion portion and the side surface (LS2). In detail, the fixing member (830) may be placed on the entire surface or a portion of the side surface (LS2).

[0181] The above-described fixing member (830) may include a resin material. The fixing member (830) is formed by applying the resin material and then curing it. The resin material has fluidity before curing. Accordingly, the resin material can flow toward the side surface (LS2). Subsequently, when the resin material is cured, the fixing member (830) can be placed on both the insertion portion and the side surface (LS2).

[0182] The thickness of the fixing member on the above side may be smaller than the thickness of the fixing member of the insertion portion.

[0183] Since the above-mentioned fixing member is also arranged on the side surface, a short circuit between the cap down and the safety vent can be prevented. In detail, the first edge region and the second edge region can be insulated by the fixing member on the side surface.

[0184] Accordingly, when an event of the secondary battery occurs, the fire of the secondary battery can be prevented from spreading due to a short circuit between the first edge region and the second edge region. Accordingly, an explosion of the secondary battery can be prevented.

[0185] Referring to Fig. 11, the buffer member (800) may include a curved surface. Specifically, at least one of the two ends (E3) of the buffer member (800) may include a curved surface. For example, the end of the buffer member (800) facing the bending portion (BA) may have a curved surface. Accordingly, the buffer member (800) may be easily inserted into the insertion portion. Accordingly, the fixing force of the buffer member (800) may be improved.

[0186] Alternatively, the end of the buffer member (800) facing the insulating member (700) may have a curved surface. Accordingly, the insulating member (700) can be prevented from being damaged by the edge of the buffer member (800). Accordingly, the safety vent and the cap down can be stably insulated by the insulating member.

[0187] Referring to FIG. 12, the buffer member (800) may include a region of varying thickness. Specifically, the thickness of the buffer member (800) may increase as it extends from the outside to the inside. Specifically, the thickness of the buffer member (800) may increase as it moves away from the bending portion (BA). Specifically, the thickness of the buffer member (800) may increase as it approaches the insulating member (700).

[0188] Accordingly, the buffer member (800) can be easily inserted into the insertion portion. In addition, the buffer member (800) can be prevented from being dislodged from the insertion portion.

[0189] Referring to Fig. 13, the safety vent may include a pattern portion. Specifically, the pattern portion (PA) may be formed in the first edge area (OA1). Specifically, the pattern portion (PA) may be formed in the insertion portion. Specifically, the pattern portion (PA) may be formed in at least one of the bending portion (BA), the first unbending portion (UBA1), and the second unbending portion (UBA2).

[0190] The above pattern portion (PA) may protrude in one direction from the surface of the first edge area (OA1). For example, the pattern portion (PA) may include a rough pattern. Accordingly, the surface roughness of the insertion portion may be increased by the pattern portion (PA).

[0191] The buffer member (800) may be placed in the insertion portion. The contact area between the buffer member (800) and the insertion portion may be increased by the pattern portion (PA). Accordingly, the fixing force of the buffer member (800) may be improved. Accordingly, the buffer member (800) may be prevented from being dislodged from the insertion portion. In addition, the adhesion between the buffer member (800) and the insertion portion may be improved. Accordingly, the deformation prevention effect by the buffer member (800) may be improved.

[0192] Referring to FIGS. 14 and 15, the first edge area (OA1) may further include a bend portion.

[0193] Referring to FIG. 14, the first edge area (OA1) may further include a third bending portion (BA3). Accordingly, the first edge area (OA1) may include a plurality of bending portions.

[0194] In detail, the first edge area (OA1) may include a first bending area (BA1) between the first unbending area (UBA1) and the second unbending area (UBA2) and a second bending area (BA2) bent at the second unbending area (UBA2). The second bending area (BA2) may be bent toward the first central area (CA1).

[0195] The end of the second bending portion (BA2) may be in contact with the first central area (CA1). Alternatively, the end of the second bending portion (BA2) may be spaced apart from the first central area (CA1).

[0196] The second bending portion (BA2) may completely or partially surround the end of the buffer member (800). Accordingly, the fixing force of the buffer member (800) may be improved. Accordingly, the buffer member (800) may be prevented from being dislodged from the insertion portion.

[0197] Referring to FIG. 15, the first edge area (OA1) may further include a third bending portion (BA3) and a fourth bending portion (BA4). Accordingly, the first edge area (OA1) may include a plurality of bending portions.

[0198] In detail, the first edge area (OA1) may include a first bending area (BA1) between the first unbending area (UBA1) and the second unbending area (UBA2) and a second bending area (BA2) between the second unbending area (UBA2) and the third unbending area (UBA3). The second bending area (BA2) may be bent toward the first central area (CA1).

[0199] The first bending portion (BA1) and the second bending portion (BA2) can be bent in opposite directions.

[0200] Accordingly, the first edge area (OA1) may include a first insertion portion and a second insertion portion. The first insertion portion may be formed between the first unbending portion (UBA1) and the third unbending portion (UBA3). The second insertion portion may be formed between the second unbending portion (UBA2) and the third unbending portion (UBA3).

[0201] The buffer member may include a first buffer member (810) and a second buffer member (820). The first buffer member (810) may be disposed in the first insertion portion, and the second buffer member (820) may be disposed in the second insertion portion. The second buffer member (820) may be prevented from being dislodged from the insertion portion by the second bending portion (BA2).

[0202] The first edge area (OA1) may include a plurality of bending portions that bend in opposite directions. Accordingly, the length of the safety vent forming the first edge area (OA1) may increase. Accordingly, the first edge area (OA1) may be stably supported by the beading portion (130). In addition, the strength of the first edge area (OA1) may be improved.

[0203] Additionally, the first edge area (OA1) may include a plurality of inserts. Furthermore, the buffer member may be positioned in each insert. Accordingly, an effect identical to or similar to that of FIG. 7 may be achieved.

[0204] Referring to Fig. 16, the first edge area (OA1) may include a plurality of patterns (P). The patterns (P) may be formed on the bending portion (BA). The patterns (P) may penetrate the bending portion (BA) in whole or in part. For example, the patterns (P) may be formed as holes or grooves.

[0205] The stress generated in the above bending portion (BA) can be reduced by the pattern (P). Specifically, the stress generated in the above bending portion (BA) can be dispersed by the pattern (P). Therefore, the shape of the safety vent can be prevented from changing due to the stress. In addition, the first edge area (OA1) can be easily bent. That is, the force required to bend the first edge area (OA1) can be reduced. Accordingly, the formation of the above bending portion (BA) can be facilitated.

[0206] Accordingly, the position or shape of the first notch can be prevented from changing. Accordingly, the secondary battery according to the embodiment can have improved lifespan and reliability.

[0207] Fig. 17 is an enlarged view of area B of Fig. 3. Fig. 17 is a drawing explaining various shapes of the first notch.

[0208] Referring to Fig. 17, a buffer portion (BP) may be arranged in an area adjacent to the first notch (N1). The thickness of the buffer portion (BP) may be smaller than the thickness of the first central area (CA1).

[0209] As previously explained, the stress generated in the bending portion can be transferred to the first central region (CA1). The thickness of the safety vent where the first notch (N1) is formed is smaller than the thickness of the first central region (CA1). Accordingly, a rapid stress change may occur in the region where the first notch (N1) is formed. Accordingly, the shape or position of the first notch (N1) may change.

[0210] The above buffer portion (BP) can prevent the above-described rapid stress change. That is, the stress passes through the buffer portion (BP) and is transmitted to the first notch (N1). Accordingly, since the change in thickness becomes gradual, the amount of stress change can be reduced. Accordingly, the shape or position of the first notch (N1) can be prevented from changing.

[0211] The buffer portion (BP) may be formed in various shapes. Referring to (a), the buffer portion (BP) may be formed with a constant thickness. Referring to (b) and (c), the thickness of the buffer portion (BP) may gradually decrease as it approaches the first notch (N1). Referring to (d), the buffer portion (BP) may have a stepped shape and gradually decrease as it approaches the first notch (N1).

[0212] Fig. 18 is a perspective view of a secondary battery according to another embodiment. The configuration of the cap assembly described above can be applied equally to other embodiments. Referring to Fig. 18, the secondary battery according to another embodiment further includes a first current collector plate (271) and a second current collector plate (272).

[0213] The first current collector plate (271) may be positioned between the electrode assembly (200) and the cap assembly (600). The first non-coated portion may be notched. Accordingly, the first electrode (210) may include a plurality of first substrate tabs (211a) formed by the first non-coated portion. That is, a secondary battery according to another embodiment does not require a separate first electrode tab.

[0214] The first substrate tab (211a) may be formed. Accordingly, a plurality of first substrate tabs may be joined to the first collector plate (271) by welding. The first collector plate (271) and the cap assembly may be joined via a lead tab (450). Specifically, the first collector plate (271) and the cap down (600) may be joined via the lead tab. Alternatively, the first collector plate (271) may be joined to the cap down (600) without a separate lead tab. Accordingly, the first electrode (210) may be electrically connected to the cap assembly via the first collector plate (271).

[0215] The second current collector (272) may be disposed between the electrode assembly (200) and the bottom portion (110). The second current collector (272) and the case (100) may be connected. For example, the second current collector (272) and the bottom portion (110) may be coupled. The second non-coated portion may be notched. Accordingly, the second electrode (220) may include a plurality of second substrate tabs (221a) formed by the second non-coated portion. That is, a secondary battery according to another embodiment does not require a separate second electrode tab.

[0216] The second substrate tab (221a) may be formed. Accordingly, a plurality of second substrate tabs may be joined to the second collector plate (272) by welding. Accordingly, the second electrode (220) may be electrically connected to the cap assembly through the second collector plate (272).

[0217] In Fig. 18, a separate insulator is not shown. However, a secondary battery according to another embodiment may further include an insulator disposed on the upper and / or lower portion of the electrode assembly.

[0218] In the above description, it was described that the first electrode (210) and the second electrode (220) are arranged at different positions. However, the embodiment is not limited thereto. For example, the first electrode tab (410) and the second electrode tab (420) may extend in the same direction. For example, both the first electrode tab (410) and the second electrode tab (420) may extend upward. Accordingly, the first electrode (210) and the second electrode (220) may be arranged at the same position.

[0219] The secondary batteries described above can form a battery module. For example, the battery module may include multiple secondary batteries. The multiple secondary batteries may be connected in series and / or parallel via bus bars.

[0220] The secondary battery and battery module according to the above-described embodiment can be used to manufacture a battery pack.

[0221] Referring to FIGS. 19 and 20 , a battery pack (3000) may include a plurality of battery modules (3200) and a housing (3100) for accommodating the plurality of battery modules (3200). For example, the housing (3100) may include first and second housings (3110, 3120) that are coupled in a direction facing each other with the plurality of battery modules (3200) interposed therebetween. The plurality of battery modules (3200) may be electrically connected to each other using a bus bar (3500), and the plurality of battery modules (3200) may be electrically connected to each other in a series / parallel or series-parallel hybrid manner to obtain a required electrical output. For convenience, components such as a bus bar, a cooling unit, and an external terminal for electrically connecting secondary batteries are omitted in the drawings. In some examples, the battery pack (3300) may be mounted on a vehicle. The vehicle may be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle. A vehicle may include a four-wheeled vehicle or a two-wheeled vehicle.

[0222] Referring to FIG. 21, the battery pack (3000) may include a battery pack cover (3010) (which may correspond to the first housing) which is a part of a vehicle underbody (4100) and a pack frame (3020) (which may correspond to the second housing) which is disposed at the lower portion of the vehicle underbody (4100). The battery pack cover (3010) and the pack frame (3020) may be formed integrally with the vehicle floor (4200). The vehicle underbody (4100) separates the interior and exterior of the vehicle, and the pack frame (3020) may be disposed at the exterior of the vehicle.

[0223] Referring to FIG. 22, the vehicle (4000) may be formed by combining additional components such as a hood (4300) at the front of the vehicle and fenders (4400) positioned at the front and rear of the vehicle, respectively. The vehicle (4000) includes a battery pack (3000) including a battery pack cover (3010) and a pack frame (3020), and the battery pack (3000) may be coupled to the vehicle (4000).

[0224] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical idea of ​​the present invention and the equivalent scope of the patent claims to be described below by a person having ordinary skill in the art to which the present invention pertains.

Claims

1. Case; An electrode assembly accommodated inside the case; and Including a cap assembly that seals the case, The cap assembly includes a cap down and a safety vent on the cap down, The safety vent includes a first central region and a first edge region, The first edge region includes an insert formed by a plurality of bends, A buffer member is placed in the above insertion portion, A secondary battery wherein the tensile strength of the buffer member is greater than the tensile strength of the safety vent.

2. In paragraph 1, A secondary battery wherein the tensile strength of the buffer member is 4 to 100 times the tensile strength of the safety vent.

3. In paragraph 1, The above safety vent is the outermost surface of the upper portion of the secondary battery.

4. In paragraph 1, The cap down includes a second central region and a second edge region, The second central region and the second edge region overlap with the first central region in the first direction, which is the height direction of the secondary battery, The first edge region and the second edge region do not overlap in the first direction, A first notch is arranged in the first central area, A secondary battery in which a second notch is arranged in the second central region.

5. In paragraph 4, The above first edge region includes a first unbending portion, a second unbending portion, and a bending portion, The above bending portion is connected to the first unbending portion and the second unbending portion, A secondary battery in which the insertion portion is formed in an area between the first unbending portion and the second unbending portion.

6. In paragraph 4, Further comprising an insulating member disposed in the first central region and the second edge region, A secondary battery in which the buffer member and the insulating member are in contact.

7. In paragraph 5, Further comprising an insulating member disposed in the first central region and the second edge region, A secondary battery wherein the buffer member and the insulating member are spaced apart by a first distance.

8. In paragraph 7, The second unbending portion and the second edge region are spaced apart by a second distance, The above second distance is 0.2 mm to 0.5 mm, The above first distance and the above second distance are different secondary batteries.

9. In paragraph 5, The above buffer member has a first thickness, The above first unbending portion has a 2-1 thickness, The above second unbending portion has a thickness of 2-2, A secondary battery in which the radius of curvature of the bending portion is 0.3 mm to 0.5 mm, and the thicknesses of the 2-1 thickness and the 2-2 thickness are 0.3 mm to 0.5 mm, and the first thickness is 0.3 mm to 0.5 mm.

10. In paragraph 1, The above first edge region has a third thickness, The above cap assembly has a fourth thickness, The above fourth thickness is a secondary battery that satisfies the following mathematical formula. [Mathematical formula] T3 ≤ T4 ≤ T3 * 1.1 11. In paragraph 4, Further comprising an insulating member disposed in the first central region and the second edge region, A secondary battery in which the insulating member is disposed on the upper surface and side surface of the second edge region.

12. In paragraph 4, A secondary battery in which the end of the buffer member does not overlap the end of the second unbending portion in the first direction.

13. In paragraph 1, The above buffer member includes a first buffer member and a second buffer member, A secondary battery wherein the tensile strengths of the first buffer member and the second buffer member are different.

14. In paragraph 1, Further comprising a fixing member disposed in the above insertion portion and in contact with the buffer member, A secondary battery in which the buffer member and the fixing member include different materials.

15. In paragraph 14, The above first edge region includes a first unbending portion, a second unbending portion, and a bending portion, The above bending portion is connected to the first unbending portion and the second unbending portion, The above insertion portion is formed in the area between the first unbending portion and the second unbending portion. A secondary battery in which the above fixing member is disposed on the side of the insertion portion and the second unbending portion.

16. In paragraph 1, A secondary battery wherein at least one end of the buffer member comprises a curved surface.

17. In paragraph 5, A secondary battery comprising a pattern portion formed in at least one of the bending portion, the first unbending portion, and the second unbending portion.

18. In paragraph 5, The above bending portion includes a pattern, The above pattern is a secondary battery that is a hole or a groove.

19. In paragraph 4, including a buffer portion adjacent to the first notch, A secondary battery wherein the thickness of the buffer portion is smaller than the thickness of the safety vent in which the first notch is formed.

20. In paragraph 19, A secondary battery in which the thickness of the buffer portion decreases as it gets closer to the first notch.

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